PHARM - Oral Medications and the Eye - Week 6 Flashcards
What route of drug administration is more likely to cause adverse effects?
Oral and injectables
How do topical eye drugs enter the blood stream (3)? Give percentages.
Direct absorption across the conjunctival blood vessels (30%)
Draining via naso-lacrimal duct, into nasal cavity, and eventually the gut (70%)
What absorption mode can give direct access to the CNS? Is it fast or slow?
Cross membranes of the olfactory nerve, is fast
True or false
All topical eye drops/ointments will be absorbed into the bloodstream.
True
Describe the double D method for minimising systemic eye drug absorption. Explain why it works briefly.
By how much does this reduce systemic absorption?
Dont open eyes for 1-2 mins (minimises conjunctival flow)
Digital puncta occlusion (reduces punctal access)
Reduces [drug] in blood by 65-70%
Is it easy for drugs to absorb into the cornea?
No, its a challenge
What is the best formulary for corneal absorption? What is a problem with it?
Acetate formulary
While it has rapid absorption, it borders on toxicity
What is the rule of thumb for eye drop formularies in order of use (3)?
Describe the general effect and duration for each formulary (if applicable).
Acetate > alcohol»_space; phosphate
Acetates are more toxic but can be at a lower dose that avoids it, the effect is short lived and may require multiple drops.
Phosphates have a slower absorption with longer duration of non-toxic therapeusis.
What are 6 classes of drugs that optometrists can prescribe?
Allergy
Anti-inflammatory
Analgaesics
Antibiotics
Antivirals
Anti-glaucoma
How can ocular lubricants be useful as an anti-allergy agent?
They can wash/remove/dilute an antigen
Can vasoconstrictors be used for mild non-specific hyperaemia?
Yes
What is a good agent to use for mild allergic conjunctivitis?
Vasoconstrictors like alpha-adrenergic agents
Give an example of an alpha-adrenergic vasoconstrictor.
Phenylephrine
What action do astringents have and what are they useful for?
They reduce mucoid discharge in allergic surface disease and is a useful anti-allergy agent
What is the hallmark of allergic eye disease?
Itch
Mast cell stabilisers are useful as what?
Anti-allergy agents
What histamine receptors are anti-histamine eye drops selective for?
H1 selective
What histamine receptors are mast cell stabiliser eye drops selective for?
H1 selective
What does pre-treatment with mast cell stabiliser eye drops result in?
Minimises expression of allergic eye disease
Are anti-inflammatory agents also anti-allergy?
Generally yes
How do NSAIDs work in the eye (3)? What agent do they act as?
Inhibit COX enzymes, decreasing prostaglandin synthesis, and reducing prostaglandin mediated inflammation.
They are anti-inflammatory agents.
Corticosteroids inhibit what pathway?
Intracellular receptor mediated inhibition of inflammatory cascade
Corticosteroids inhibit the activity of what two cells in the eye?
Fibroblast and keratocyte activity
List two examples of antimetabolites and what agents they act as.
Calcineurin and T-cell inhibitors
As anti-inflammatory agents
What is a good rule of thumb on treating eye inflammation?
If it is no deeper than the iris, topical therapy should suffice.
What should be considered if inflammation is deeper than the iris (4)?
Oral, intraocular/sub-conj./sub-Tenon’s injection
The use of what drug class will control post-op cystoid macular oedema? Describe why.
Topical use of NSAIDs
It inhibits PG production in the anterior eye, rather than the retina, and will reduce overall ocular PG load at the posterior pole
Are steroid complications more or less likely with long duration of use?
More likely
Does topical steroid use promote or inhibit microbial activity? How does it affect would healing?
Promotes microbial activity
Delays would healing
List 5 ocular related adverse effects that occurs with long-term topical steroid use.
Increased IOP - glaucoma
Cystoid macular oedema
Rebound inflammation
Aggravated dry eye
Cataract
How should steroids generally be used?
Use them hard to suppress inflammation but only for short terms <4 weeks
List 3 ocular related adverse effects that occurs with long-term periocular steroid use.
-as for topical use
Ptosis
Scleral melt and perforation
List 6 adverse effects that occurs with long-term oral/systemic steroid use.
Weight gain
Peptic ulcer
Opsteoporosis
Diabetes
Hypertension
Cushing syndrome
Describe a possible dietary link to inflammation. Comment on essential fatty acids 3 and 6, as well as the Western diet in this context.
Cell membranes produce free fatty acids in the presence of PLA2, which is produced in large amounts during inflammation.
n-6 pathway favours pro-inflammatory cytokine production.
n-3 pathway favours anti-inflammatory cytokine production.
The western diet has a high intake of n-6.
What can be used for pain in the case of iritis or uveitis?
Cycloplegic agent
Is penicillin commonly used in eye care?
Rarely
What is the second line drug for most eye/eyelid infections? Why?
Amoxycillin - due to adverse effects
List an adverse effect of amoxycillin.
Hypersensitivity reaction - mostly skin rash
What is the first choice ophthalmic drug for eye care and why?
Cephalosporins due to low adverse effects
Are cephalosporins bactericidal or bacteriostatic?
Bactericidal
List two adverse effects of cephalosporins.
Allergy/hypersensitivity
Prolonged use can impair blood clotting
What is a possible consequence of using cephalosporins?
It can destroy GI bacteria that synthesise vitamin K, which is why long term use can impair blood clotting
Given its adverse effects, in which individuals are cephalosporins contraindicated?
Haemophiliacs
List two examples of macrolides. Are they bacteriostatic or bactericidal?
Erythromycin
Azithromycin
Are bacteriostatic
Are macrolides used in eye care? Explain.
Not generally, as they are bacteriostatic
Good anti-infective for chlamydia however
What infection are macrolides good for, how do they work (briefly), and what is the alternative if contraindicated?
Good for chlamydia
Work by inhibiting protein synthesis by binding 50S
Tetracyclines the alternative
What is the most effective tetracycline in eye disease and why is its use limited?
Doxycycline - limited due to bacterial resistance
How does doxycycline act.
Inhibits protein synthesis by binding 30S
What tetracycline has the fewest adverse effects?
Doxycycline
What antibiotic has an effect on meibomian glands and what does it do (2)? How is it used in this context and how long?
Doxycycline - alters MG function and tear flims
Used long term (up to 6 months) for dry eye disease
What antibiotic has excellent broad spectrum properties and is only reserved for serious corneal infections? What drug class does it call under? Is it bacteriostatic or bactericidal?
Ciprofloxacin - bactericidal by inhibiting DNA gyrase
What are two corneal adverse effects of ciprofloxacin?
Slows corneal healing and promotes perforation
What antibiotic drug class is reserved for the more serious eye infections?
Fluoroquinolones
Briefly explain how guanine analogs work (4) and what they are.
They are antivirals.
They are prodrugs that are activated into a monophosphate by viral thymidine kinase
They then undergo phosphorylation to triphosphate by host kinases
It is incorporated into viral DNA, which terminates replication
What are guanine analogs activated by and into what form?
What happens it it after that and by what?
Viral thymidine kinase to monophosphate form
Phosphorylated to triphosphate by host kinases
Why are guanine analogs effective as antivirals?
Viruses have fast replication - the effect is large and desirable
Why are adverse effects generally minimised when taking guanine analogs?
Healthy human cells have slow replication as opposed to viruses, minimising adverse effects
What is a common side effect of guanine analogs?
Some SPK
How can guanine analog side effects be further reduced?
Effects on human cells can be reduced by using them for a limited time
What are three indications for guanine analog use?
Treatment/prevention of herpes simplex virus
Shingles
Chickenpox in immunocompromised individuals
How are drugs for herpetic eye infection administered? Can oral be used for acute treatment?
As an ointment
Oral not used for acute treatment
Give two examples of a guanine analog.
Which has better absorption/bioavailability?
Acyclovir and famcyclovir
Famcyclovir has better basorption and bioavailability
When treating shingles, within what timeframe of symptom onset must the treatment be started?
Within 72h of symptoms manifesting
Which has a better safety profile, acyclovir or famcyclovir?
Famcyclovir fam
Is famcyclovir available in Australia for eye treatment>
No fam, just acyclovir
Which is more cost effective - oral acyclovir tablets or acyclovir ointment? Explain.
Oral therapy is more expensive and not cost effective over ointment - EXCEPT in children
Name two ways IOP can be lowered.
Decreasing aqueous production
Increasing drainage
How can aqueous production be lowered (2)?
By targetting adrenergics aB and carbonic anhydrase inhibitors
List 6 reasons why children rceive excess dosage (if going by adult doses).
Smaller eye
Greater absorption of drugs in children
Immature metabolic pathways
Dose not tailored for children’s mass
Eye dropper volume is too large for children
Smaller blood volume gives greater circulating dose
What magnitude does a child’s smaller blood volume increase circulating drug dose?
x20
What drugs are safe for children >2 years of age (2)?
All of them except anti-histamines
What glaucoma medications should be avoided in children (2)?
Avoid alpha agonists if <2
Avoid beta blockers
What are two danger signs with kids?
Loss of vision
Fever (red eye)
Most childhood red eyes are what?
Viral infection
What is an intense sudden onset of pain indicative of?
FB/abrasion
If a child has an abrasion, is patching recommended?
No
What is a good way to see if anaesthetic has been administered onto a crying child’s eye?
Fluorescein/anaesthetic combo - load it onto the crying eye and use fluorescein to check
What is recommended for pain in children (in their eye obviously)? If it doesn’t resolve after 24h, what is recommended?
Homatropine
If unimproved after 24h, suspect internal FB
What should you always consider if a child has pain in their eyes?
Internal FB
What is a common cause of naso-lacrimal duct obstruction in children?
Age related imperforate membrane at distal end
What should not be missed concerning a naso-lacrimal duct dysfunction?
What is it, and what is the recommended action (3)? Are antibiotics given?
What if it hasnt resolved after 13 months?
Red, purulent discharge from the duct
Indicates dacryoadenitis
Needs parental reassurance of 90% remittance by 1 year
Lid hygiene, heat/massage
No antibiotics are given
Probe or refer if unresolved after 13 months
What is advised for insect bites?
Anti-histamines
Are antibiotics used for children with conjunctivitis? What is the best therapy? Why is this so (2)?
Yesd
Best therapy is delayed antibiotic (3 day)
Produces less drug resistance and allows the body to heal
True or false
All eye drops will cross the placenta and have the potential to harm to foetus.
True
Are all anti-infectives safe to use in pregnancy and lactation?
Yes
Are NSAIDs a concern for pregnant women?
Short term low dose - no
Are steroids safe to use in pregnancy?
Category A is safe
What can be said of glaucoma and anti-glaucoma drugs in pregnant women by trimester?
IOP usually decreases in the 2nd and 3rd trimesters due to hormonal effects
Initial high IOP is acceptable
Are dilating drops safe to use in pregnant women?
Yesd
True or false
All drugs secrete into breast milk with potential for side effects.
True
If a mother is taking b-blockers while lactating, what must be done?
Child’s pulse must be monitored for bradycardia
